A sodium street lamp gives out yellow light.
Inside the lamp, electrons in sodium atoms gain energy and move to orbits further from the nucleus. The electrons then move back to orbits closer to the nucleus.
Explain how the electrons moving back to orbits closer to the nucleus cause the lamp to give out light.
The light from the lamp is produced by electrons moving between the same two orbits. The light is always the same colour.
Explain why.
Some electrons gain so much energy that they leave their atoms completely.
Give the name of the particle that is left behind when an electron leaves a sodium atom.